Method of blanching food products



" 2 SAh`eVetS-Sheet 1 INVENTOR.

D. M. MCBEAN Filed Oct. 5, 1942 METHOD OF BLANCHING FOOD PRODUCTS Y July 9,1946. D, M. McBEAN `2,403,871

METHOD OF BLNCHING FOOD PRODUCTS 4 Filed oct. 5. 1942 2 'sheets-sheet 2 v l v I INVENTOR agghslean )mb/FJWW 5 flame Patented July 9, 1 946 UNIT ED STAT E s PATE NT oF'FiC-E VWETIIOD F BLANCHING FOOD PRODUCTS Douglas M. McBean, Rochester, N. Y. Application October 5, 1942,-Ser`ial No. 460,918

My invention relates to a method and apparatus for blanching food products. The method and apparatus of my invention may be employed in any of the conventional processes of food preservation, such as canning freezing or dehydration.

An object of my invention is they provision of an improved process of blanching and an apparatus for carrying out vsaid process, wherein the temperature at which the edibles, such as fruits, vegetables, meats andiish, arebianched and the time during which such blanching occurs maybe more accurately controlled. p

Another object of my invention is to provide an improved processgof Iblanchirig, wherein the edibles are maintained injconstantp'ositive"mo-l I cessive batches of edibles are segregated and sepe arately treated by' the direct-action of steam and while maintained in continuous motion, the steam being preferably underfpre'ssure and the pressure being 'gradually reduced toward the en'dof the blanching process.

stiuenotner object of my invention is' the ero'-` vision of a'inethod ofcontinuous blanching 'and an apparatus for carrying outsaid method wherein the food product is heated under pressure in relatively small "pressure vessels-or retorts each segregated fromthe other :to vthe endy that the blanchingV medium may more lreadily and more uniformly permeatel the product Vand so that cold spots and improperly blanched portions of the foodrproduct are avoided.V

My invention further has for an object the provision ofamethod of continuousblanching and an apparatus for carrying out said method wherein exhaust steam or steam which has already been used for blanching may be yemployed to flushl or blow air out of the pressurevessel or retortV into which the unblanched food product is charged;

My inventionv further contemplates 4the provision of apparatus adapted to carry out myv novel process ofY blanching wherein the foodrmay be blanched in segregated batches' in separate com- Y partments by steam under-pressure^with con'-` Claims. (Cl.v 99-103`) f2 1 veying means 'being provided to maintain the compartments, including "the redibles and the steam, continuously'in motion from a charging point to a discharging point. Y f

othery objects and advantages of my invention will loev setforth in the Aclaims and will be apparent from `the following description,v when taken in connection with the accornpany'ing drawings, in which; v k .p

Fig. *1*V is aside elevation Vof' the' apparatus' of 'my invention;A Y i Fig. 2 is ra partial 'sectional lView `of' the piston and connecting chainv assembly;`

vFig. 3 is a face view of one of thepistons;

Fig. 4 isa face View of one' of the sprockets for driving `the `chain assembly;v Y

Fig. 5 is a sectional View taken substantially on the'iine 4 4 of Vvlig."5; and

"Fig, 6 `is aT view similar' to Fig. 4 `s'howving aA modi'fied iormMofzthe piston andjehain assemblyof my invention.

In thejpreservation -of most food products Yby canning, ireeZing, lorV dehydration, it is'. necessary to `inactivate 'the 4,percidase and eatalase sys;V

tems` of' the food product. In. 4this conventie:ral enzymeinactivation process, which isknown as blanchingit iscustomary toheat .the edibles to a predetermined temperature for a'predetermined period of' time by the use. of 'steam or not water; The accurate -control of the tempertaure vtime relationship' is extremely importantin order that the Venzyines may be thoroughly inactivated withoutinj-uring the edible as a food. Within reasonable temperature limits thelolaneinngteniperature. may be increased, .but in such case the .time

. should'be' decreased toprev'ent the destruction or loss Vofl valuable Vfood properties vof thel edibles. Moreoveniithas been generally found desirable by those skilled" in the art that it is oradva'ntage to quicklyfinactivatethe enzymesfby employing higher-g' temperatures and 'a shorter blancning timel `The temperature and `time variations which are permissible are well 'knownin'the art to which this invention applies Aand vaiyrsomewhat 'with Vthe species of kfood lprecinct bein-g blancned and .the sizeof' the pieces. i 1

The advantages A of continuous proef-iss"r nover hatchl processes of lo'lanclni'ngA haweaIsoloeeirreeognizeclf The' 'continuous process 'not only" re#- quires-le'sssteain or hjotwater, vbuta'lso el'ects a g tremendous saving in' labor and equipment inthe handling of thefoodprdouct. 'Aifurtner-impor-Y v tant advantagel of the continuous process' of blanching is'that thetemperature of the product can :be quickly raised suci-entl-y to inactivate t the cutting or dicing operation and the blanching operation. The time interval between cutting and blanchingis important for the reason that after cutting there is a very rapid loss from the vegetable or other food product of ascorbic acid and other essential Vitamins.

Insofar as I am aware, the present continuous processes of blanching do not enable the desired accurate control of the temperature time relationship With respect to each particle or portion of the edible being blanched. Where a large volume of the food product is exposed to the blanching medium uniformity of blanching, between diierent portions of the mass, is difficult to obtain. I have found that more acurate control of the temperature time relationship may be obtained, while still carrying the process out in a continuous manner, if the edibles are blanched in small segregated batches in separate pressure vessels or retorts, with the batches being moved continuously at a predetermined rate of speed predetermined in accordance with the temperaturel of the heating medium. 'Moreoven in such a system of pressure blanching I provide means gradually to reduce the pressure on the edibles near the end of the blanching cycle and also provide means enabling the vuse of exhaust steam :1,

for driving as much air as possible away from contact with the edibles.

For the purpose of carrying out the method of my invention I have shown in Fig. 1, in a somewhatV diagrammatic manner, an apparatus suitable for this purpose which comprises a cylindrical or other shaped tube II through .which a chain or other continuous belt `I2aV passes. The cylindricaltube' II may be made in separate sections, as shown in the drawings, 0r may be made in one piece and is preferably of a length sufficientto carry out -the complete blanching process while the edibles are carried through the tube. The chain I2va is mounted on suitable sprockets I2, vone of which may be driven by any suitable prime mover (not shown). Preferably'the chain conveyor isdriven by a prime mover the speed of which may be varied so that the time of blanching may be accurately controlled and regulated.

Mounted on the chain conveyer is a seriesY of spaced pistons I3 which are of a diameter such as to Vfit snugly the internal diameter of the tube I I. The pistonsare adapted to form the end walls of a series of compartments, indicated by the numeral I4. The end walls and the inner wall ofthe tube form segregated blanching chambers or pressure vessels for the reception of the `food products.k The amount of food Vproduct each lblanching chamber will carry is dependent upon its size and the 'speed'of the conveyer. For different food products it may be desirable to vary thesize of, the blanching chambers soA as to increase or decrease the size of the batches.

The pistons I3, as shown most clearly in Fig. l--

2, may be made of wood reenforced by suitable facing plates I6 through which extend rivets II. Each of the ypistons is provided with a central bore through which a connectinglink lI8 extends.

Theconnecting link I8 pivoted adjacent its Gil ends, as indicated at I9, to links of the chain to form a continuous assembly. For purposes which will appear later the length of the connecting link from pivot to pivot is a multiple of the pitch of the chain. In the particular illustration shown a ratio of six to one is employed, although it will be apparent that this may be varied.

For the purpose of preventing leakage between the external diameter oi the connecting link and the bore of the piston, a seal 2I is provided at one 0r bothends of theconnecting 1-link I8. In the chain and piston assembly, illustrated in the drawings, I have shown a single connecting link passing axially vof the piston. With some vegetables as, for example, lsauerkraut, it may be desirable to employ two chains with two connecting links extending through the pistons. If two connecting links and chains are employed they are spaced so that the connecting links extend through the pistons adjacent the peripheries thereof. This arrangement minimizes the Wrapping of the Sauerkraut around the chain.

The tube II may be supported in any suitable manner, as by a frame structure 22 upon which the bearings or Supports 23 for the sprockets may also be mounted. The tube, at its entrance opening has a tapered mouth piece 2d adapted to guide the pistons and properly center them with respect to the tube as they successively enter the tube. Adjacent the entrance end of the tube is a hopper 26 which has a free opening 21 into the tube.

The usual practice in blanching is to rst wash the edibles and then slice, dice, or otherwise cut up, for example, the vegetables into small pieces so that the heating medium maymore readily penetrate to the center of the ypieces for the purpose or" thoroughly inactivatingthe enzymes. After the edibles have been thus prepared they are preferably immediately dumped into the hopper and as the conveyer moves, each piston or pressureA vessel picks up a charge or batch of edibles and carries such batch along the tube. Since each compartment is substantially sealed by the pistons from its adjacent compartment, there is a minimum loss of heating medium and also eachrbatch of edibles is segregated and seharately treated., With this arrangement more accurate control ofthe temperature to which each particle is heated may be maintained and cold spots and inadequately blanched portions of the mass are avoided.

Extending through the .walls of the tube are a series of openings 28 through which steam may be introduced. desired number of steam openings may be employed depending upon conditions. Although steam is the preferred blanching medium, it might be possible to use the apparatus of my invention with a hot water blanching medium. I have foundthat better heat transier to the edibles being blanched may be obtained when the edibles are subjected to the direct Contact of the heating medium. An importantl aspect of the invention is that the product being blanched and the heating medium are in positive motion` which facilitates circulation of the steam between the pieces of material and tends to produce a uniformity in the temperature towhich each particle oi food is heated.

The preferred temperature range for carrying out the bianching process is' from approximately 296 F. to 220 F.` .The higher the temperature the more rapid the chemical reaction resulting in enzyme inactivation, and with my method and apparatus. for blanching high temperatures and blanching. This temperature time relationship:

will, of course, vary-for-dilferent food products as iswellknown inthe art. To heat the vegetables tothe above temperatures somewhat higher steamr-temperatures are required. While a uniform'temperature and pressure of steam may be employed substantially throughout the blanching. process, the pressure should be dropped near the endl of the cycle to prevent the cells of the vegetables from disintegrating as a result of the explosive action Yof moisture in the cells caused by a suddendrop-in pressure. This is accomplished by means vwhichwill be presently described.

Instead of employing a uniform temperature and pressure substantially throughout the blanching cycle, I have found in sorne cases that it is preferable to gradually increase the temperature and pressurerat thebeginning of the blanching cycle and then gradually decrease the temperature and pressure toward the end of the cycle. Y

It willbe appreciated that such variations in the temperature-require adjustments of the speed ofthe conveyer so as to adjust thefblanching time'tothe'temperature. For example, it might be desirable to introduce steam through the rst opening 28 kat one pound pressure, at a tein- Aperature corresponding to that pressure, and

through the second opening 29 at two pounds pressure at a temperature corresponding to that pressure, -thus gradually increasing the pressure until'th'e `maximum pressure desired is reached. Similarly the pressure and temperature may be reduced in steps toward the end of the cycle. While asteam pressure of four pounds is usually sufcient, with some-edibles it may be desirable to use steam pressures as high as twenty pounds and a steam temperature corresponding to that pressure.

@ne of the important features of my inven-` =tion is thev means provided for gradually reduc-k ing the pressure on the edibles so as to prevent Y the cells thereof from exploding as a result of too rapid a drop in pressure. Such means comprises a by-pass 3| which has access, as indicated at 32, to the tube. As the compartments successively are brought into communication with the by-pass, steam may flow through the by-pass to gradually reduce the pressure in the compartment in communication with the by-pass. The gradual reduction in the pressure is accom-l plished by reason of the fact ythat there is a resistance to now of steam through the by-pass, which is effective to `control and prevent the rapid fluctuation in pressure and instead gradually reduce the same.

The by-pass 3| is extended toward the entrance end of the tube where it communicates therewith,y as shown at 33. I have found i1; extremely desirable to drive off as much air from contact with the edibles as possible. The air to some extent insulates the vegetables. Better heat transfer and penetration of `the edibles is obtained if the amount of air in the compartments is 'reduced to a minimum. Moreover, the presence of air and other non-condensable gases in the blanching chambers reduces the temperature ltherein for a given steam pressure. By thoroughly flushing out the blanching chambers with exhaust steam, the temperature gradient 4B ofthe sprocket.

openings 28 and the desired temperature vof the foodproduct, is reduced to a minimum. Thus steam, which would normally be wasted, flows through the by-pass 3|, enters the compartments successively and drives or flushes the air out through a vent 34. `It will be noted'thatthe bypass enters ther tube 33 and the vent 34 is located so that the following piston passes the right hand edge of the hopper before both the by-pass and the vent 34 have access to the compartment adjacent thereto. When the edibles reach the end of the .tube they are discharged through a discharge opening 36'and may be picked up bya conveyer (not shown) which may be located beneath the discharge opening 36.

As .previously mentioned, the connecting links I8 are, in length, a multiple of .the pitchof' the chain. To enable the chain, together with the pistons, properly to pass around the spro'ckets and/be. driven thereby, a novel sprocket construction is employed, clearly shown in Figs. 4 and 5. Each sprocket comprises a plate 4| having teeth 42 adapted to enter the openings-.in the chai-n for ,thev purpose of driving the same. LSpaced around the periphery of the sprocket area plurality of cut-outs 43. V'lhenumber of cut-outs employed maybe varied, .but inthe example shown four vcut-outsare provided. The. distance around the necting links of the adjacentl portions of-'the chain tend to assume a chordal position orto sag below the lcircle defined by the radius' of the sprocket?r Thus thel piston, together with its associated chain, attempts to lie along thefshorter distance between, for example, the points 41 and This interferes with the proper meshing of the teethof the sprocket with the openings in the links ofl ther-chain and may resultin improper mating and jamming. For the purpose yof preventing this, on` each side of thesprocket adjacent each of Ethe cut-outs there is provided a plate 49. The plates 49 form together a semi-circular support in which a piston may lie. That is, the radius of the semi-circle formed by the plates 49 corresponds substantially to the radius of the piston.

The plates 49 are secured to the sprocket by means of nut and bolt assemblies 5| which extend through openings in the sprocket and through elongated openings or slots 52'in the plates 49. LThus vthe plates may be` adjusted radially with respect to the sprocket. By proper adjustment the pistonsA may be supported in an outward position so that inthe position of support the combined length of chain .from the point 41 tothe connecting link pivot, the length of the y, chordal or sagging position from the'points 4-1 and 48 and proper meshing of the teeth of the sprocket with the chain is obtained.

This proper mating of the teeth of the sprocket with the openings in the links of the chain may also be obtained (instead of in the manner described above) by shortening the length of the connecting link, as illustrated in Fig. 6. In this method, the chordal distance across the cut-outs is measured and the length of the connecting link I8 is made such that the connecting link, together with the adjacent chain links, will assume a chordal portion across from the point 41 to the point 48.

While I have described my novel process of blanching and have shown a novel apparatus suitable for carrying out said process, it will be appreciated that various changes and modications may be made therein, particularly in the form and relation of parts, without departing from the spirit of my invention as set forth in the appended claims.

I claim:

l. A method of blanching edibles which comprises forming a series of closed chambers adapted tol contain the edibles being blanched, admitting a heating medium to said closed chambers, and continuously moving said closed chambers together with the edibles.

V2. A method of blanching edibles which comprises forming a series of closed chambers adapted to contain the edibles being blanched, admitting a heating medium of a blanching temperature under pressure to said closed chambers, and continuously moving. said closed chambers together with the edibles.

3. A method of blanching edibles which comprises forming aseries of closed chambers adapted to contain the edibles being blanched, admitting a heating medium to said closed chambers, and continuously and positively moving said closed chambers together with the heating medium and the edibles.

4. A method of .blanching edibles which comprises orming a series of closed chambers adapted to contain the edibles being blanched, substantially sealing said chambers against communication between them, admitting a heating medium to said closed chambers, and continuous- 1y moving the edibles.

5. A method of blanching edibles which comprises forming a series of closed chambers adapted to contain the edibles being blanched, substantially sealing said chambers against communication between them, admitting a heating medium at a blanching temperature in a gaseous form and under pressure to said closed chambers, and continuously moving said closed chambers together with the edibles and the heating medium.

6. A method of blanching edibles which comprises moving said edibles through a blanching cycle, subjecting said edibles to a heating medium at blanching temperature and under pressure as the edibles are continuously moved, and gradually reducing said pressure toward the end of said blanching cycle.

7. A method of blanching edibles which comprises moving said edibles through a blanching cycle, subjecting said edibles to a steam heating medium at blanching temperature and under pressure as the edibles are continuously moved, and gradually reducing said pressure toward the end of said blanching cycle.

8. A method of blanching edibles which comprises moving said edibles through a blanching cycle, subjecting said edibles to a steam heating medium at blanching temperature, and subjecting said edibles to a gradually increasing pressure at the beginning of said blanching cycle and a gradually decreasing pressure toward the end of said blanching cycle.

9. A method of treating a food product which comprises forming a series of closed chambers adapted Vto contain the food product, directing a fluid heating medium under pressure into said closed chambers and into contact with the product, and continuously moving saidclosed chambers together with the food product.

10. A method of treating a food product which comprises forming a series of closed chambers adapted to contain the food product, directing a fluid heating medium under pressure into said closed chambers and into contact with the product, and continuously and positively moving said closed chambers together with the food product from a chamber charging point to a chamber dis'- charging point.

DOUGLAS M. MCBEAN. 

